The present invention relates to systems and methods for efficient bit rate alteration of a bitstream to match an available channel capacity. The efficient bit rate alteration includes selective re-quantization of the compressed bitstream. Selective re-quantization according to the present invention applies multiple re-quantization schemes to different portions of a bitstream. In one embodiment, the multiple re-quantization schemes each have a different computational load. By selectively choosing which type of re-quantization is performed on each portion, efficient bandwidth scaling and data transmission may be achieved both when computational capacity is limited and when video data integrity is important.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for converting the bit rate of a compressed bitstream to use an available bandwidth of a channel, the method comprising: re-quantizing a first portion of the bitstream that includes a B frame including video data using a first re-quantization scheme that does not decode the first portion into a pixel domain; and re-quantizing a second portion of the bitstream that includes a P frame including video data or an I frame including video data using a second re-quantization scheme that includes full decoding and re-encoding of the second portion.
2. The method of claim 1 wherein the first re-quantization scheme includes basic re-quantization.
3. The method of claim 1 wherein the compressed bitstream is an MPEG compressed bitstream.
4. The method of claim 1 further including determining the available bandwidth of the channel.
5. The method of claim 1 wherein the second re-quantization scheme creates a new motion vector for the second portion of the bitstream.
6. The method of claim 1 further including changing the resolution of the second portion.
7. The method of claim 1 wherein the first and second portion each include a frame of the video data.
8. The method of claim 1 wherein the first portion includes a P frame and the P frame is the last P frame in a group of pictures.
9. The method of claim 1 wherein the first portion comprises color video data.
10. The method of claim 1 wherein the second portion comprises brightness video data.
11. The method of claim 1 wherein the first and second re-quantization schemes are performed in real time.
12. The method of claim 1 further including monitoring the processing load of a processor in a network device.
13. The method of claim 1 wherein the second re-quantization scheme re-uses a motion vector for the second portion of the bitstream.
14. A system for converting the bit rate of a compressed bitstream to use an available bandwidth of a channel, the system comprising: means for re-quantizing a first portion of the bitstream that includes a B frame including video data using a first re-quantization scheme that does not decode the first portion into a pixel domain; and means for re-quantizing a second portion of the bitstream that includes a P frame including video data or an I frame including video data using a second re-quantization scheme that includes full decoding and re-encoding of the second portion.
15. The system of claim 14 wherein the means for re-quantizing the first portion is included in the means for re-quantizing the second portion.
16. The system of claim 14 wherein the means for re-quantizing the first portion includes means for performing basic re-quantization.
17. The system of claim 14 wherein the means for re-quantizing the second portion includes means for performing motion compensated re-quantization.
18. A computer readable medium encoded with computer executable instructions for converting the bit rate of a compressed bitstream to use an available bandwidth of a channel, the computer executable instructions comprising: instructions for re-quantizing a first portion of the bitstream that includes a B frame including video data using a first re-quantization scheme that does not decode the first portion into a pixel domain; and instructions for re-quantizing a second portion of the bitstream that includes a P frame including video data or an I frame including video data using a second re-quantization scheme that includes full decoding and re-encoding of the second portion.
19. An apparatus for converting the bit rate of a compressed bitstream, the apparatus comprising: memory, a processor coupled to memory, the processor configured to re-quantize a first portion of the bitstream that includes a B frame including video data using a first re-quantization scheme that does not decode the first portion into a pixel domain and re-quantize a second portion of the bitstream that includes a P frame including video data or an I frame including video data using a second re-quantization scheme that includes full decoding and re-encoding of the second portion.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 18, 2001
January 13, 2009
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.